Without screen shots of the original Contrast Boosted version showing in LR and another of the exported version and another showing the export dialog window with all your settings there isn't much anyone can help with.

I just did a test on a TIFF file where i increased the contrast, excessively, and other settings then exported it as a JPG and had open PS CC 2018 selected and what came up in PS ﻿was the exact same image as what is being displayed in LR, although as a JPG.The only thing I can think of is the drop in file size or somehow the edits aren't being added to the TIFF file when exported.Try this. Instead of Exporting right click on the edited TIFF and select Edit In PS CC 2018 and when the dialog box comes up asking if you want to open original or Copy With LR Edits select With LR Edits and see what get delivered to PS.

What are your Detail panel settings and camera ISO for this image? High
ISO images that have been over-sharpened and/or have insufficient
Luminance NR will appear lower in contrast and less sharp when resized or viewed at less than 1:1 in the Library module (vs Develop module
view).